Continuous digester chip level indicator



June 8, 1954 Filed Dec. 6, 1951 D. N. OBEN-SHAIN CONTINUOUS DIGESTER CHIP LEVEL INDICATOR 5 Sheets-Sheet 1 Snnentor 0/ we N062 OBEA/J/MIM tornegs June 8, 1954 D. N. OBENSHAIN 2,680,298

CONTINUOUS DIGESTER CHIP LEVEL INDICATOR Filed Dec. 6, 1951 5 Sheets-ShaaLZ nnentor DAV/0 M054 OJE/VJf/Al/V June 8, 1954 D. N. OBENSHAIN 2,680,298

CONTINUOUS DIGESTER CHIP LEVEL INDICATOR Zmventor DAV 0 A/aez 05N5HAIN Gttornegs June 8, 1954 D. N. OBENSHAIN CONTINUOUS DIGESTER CHIP LEVEL INDICATOR 5 Sheets-Sheet 4 Filed Dec. 6, 1951 Ihwemor 0/1100 A atz 05F/VJ7/A/A/ mam (Ittorne Patented June 8, 1954 CONTINUOUS :-DIGE STER. -.CHIP LEVEL INDICATOR David Noel ObenShain, Piedmont; W. Va., assignor to -West VirginiwPu'lp'an'd Paper Company, .NewYoi kgN. Y., a. c'orporationl'of Delaware 'Application December 6, 1951,.Serial'No'. 260,271

9'Claims. 1 "My present invention relates to level-indicating and regulating devices for piles "of divided solids or semi solids and is applicable generally'to such 'material, the nature of which is such that a floatactuated device cannot be used. More specificallymy invention relates to devices for indicating thelevel of chips in a digester for makingpulp and isparticularly applicable'to situations wherein'the pile of material is enclosed within a liquid filled pressure vessel, for example.

"Itis therefore a principal object of my invention' to provide a level indicator employing a feeler device or tamper making periodic contact withthe pile and having means for registering the level of the pile as revealed by the lowermost travel of the tamper. It is a further. object of my invention tohave such registering means actuate an improved servo-mechanism acting to operate a conventional feed mechanism to alter "the height of the pile. Other objects of my invention and advantagesxthereof will be apparent as the description proceeds.

My invention will be best understood by reference "to the following detailed description taken with the annexed drawings; in which Figure 1 is a fragmentary plan .viewof a preferred embodiment of the indicatoriandservomechanism with'the digester shell'cutaway so as toreveal the feeler and feeler arm; I

Figure 2 is a fragmentary view in vertical ele- "vation similar to Fig. 1, also having the digester cut away to-reveal the feeler and feeler arm;

"Figure 3 is an enlargedview taken'on line 3+3 "of Fig. 1 of so much of the device as is outside *the'digester;

"Figure 4 is an enlarged-view in vertical section taken on line 44 of Fig. 3;

Figure 5 is aview taken on line 5-5 of Fig. 3; and

Figure 6 is a sectional view taken on line 6-6 of Figure 5,

Figure '7 shows a digester with my improved "level indicator-regulator attached;

Figure 8 shows an alternate servo mechanism for actuating the flow controller; and

"Figure9 is a circuit diagram'for the-device of "Fig. 8.

' Reference to Figures 1 and 2 showsthe feeler *ortamper I0 which is brought toward and away from the pile I I within the shell I 2 of the digester by means of the feeler arm I3 attached to shaft *l iby any suitable means, as by the usual split collarand key arrangement usual in the art.

Figure 3 shows howthe device as a'whole may be attached to the digester bymeans "of anou-ter "said drum is freely rotatable .on shaft :35. -to shaft is a second or positioner drum 56.120 which is attached vane 5i. Positioner dr-iim l5?) sleeve I5 extending'through the digester wall 12 and welded thereto. The shaft I4 is contained within a second sleeve I6 within sleeve I5, said shaft passing through a bearing I! at one end and a bushing I8 at the other end containing packing I9 and packing follower 20. Welded to sleeve I6 is a flange 2| integral with housing 2Ia, flange 2| being connected by gasket 22 to the "flanged end of sleeve I5 against which is disposed a flange ring 23. By connecting the flange ring 23 with the flange-2| by bolts 24, the entire assembly may thus be held securely to the digester shell I2.

It will be understood that means will be provided to rotate shaft I4 so as to rise-the feeler, and topermit the feeler to descend freely (through liquid if present) into contact with the pile II. Means for accomplishing this will now bedescribed.

To thus actuate the shaft, a pair of rocking links 36, 39" '(Figs. 6, 5 and d) are rocked by being joined to a connecting rod 3|, through pin 32, the other end of the connecting rod 3| being attached to crank head 33 driven by motor 34.

1' It will be noted that the rocking links 30,

are journalled on the shaft I4 by means of ball bearings 35 and hence move freely of said shaft.

Keyed to said shaft however is rocking arm. lever 35 which rests on the top of connecting rod; 35,

"as'best shown in Fig. 5. Therefore theupward. movement of connecting rod 3! will lift the feeler I 0 but will have no connection therewith on its downward stroke provided only that the pile is high enough to interrupt the downward fall of the feeler before it reaches the bottom of its stroke. Actually the downward travel of the feeler III may be limited by a stop 31 against which the rocking arm lever 36 will strike'if allowed to descend sufficiently far.

In order to register the impulse created by the limited downward travelof' the arm 35 andhence the height or level of the pile, the following mechanism is provided; arm'SB has a rearward extensioninthe'form of an car 38 to which is pivoted a 1inki39 by means of which to actuate the indi- "cator-transmitter' mechanism which is housed in "housing 40 above housing 2m for the actuating mechanism above described.

injournals -46, 4i. Pivotally connected with. link A shaft 25 rotates '39 by means of an arm 48 is a first drum or hub 49, whereby the rocking motion of the arm 36 is reproduced in said drum 49, it being noted that Keyed 3 is normally held against rotation by means of a brake 52 pivoted at pivot 53 and urged against the drum by spring 55, the tension of which is adjustable by means of screw 56 and nut 5'! held on a bracket arm 58. Brake 52 is periodically released whenever connecting rod 3| reaches the bottom of its travel, for the reason that link 59, pivoted to rocking arm (see Fig. 6) and having an adjustable tip 60, strikes the brake arm to the right of pivot 53, therebylowering the brake and freeing the drum 50. The drums 49 and 50 are resiliently connected as follows: Brake controlled drum 50 has attached thereto a pair of leaf springs noted by 5|, 6|, the same embracing the shaft and having ends fixed to a boss 62 on the drum 5!). Drum 49 has a pin 63 which when moved to the left causes the leaf spring 6| to move with it (but not the drum 5!], since it is held by the brake 52). Therefore the position of the leaf spring 5| will register the end of the down stroke of feeler l0. Assuming that the top of connecting rod 3| continues to move downwardly (as it will since desirably the stop 31 will interrupt the downward move of arm 35 a slight distance above the lowermost travel of the top of connecting rod 3|), the link 5S will operate to release the brake 52, thus allowing drum 5!) to move so as to enable the leaf springs to assume the closed position in which the same are both in contact with the pin 63. Thereby the position of drum 5!! and the vane 51 will be de termined by the lowermost travel of the feeler l0, whereby position of vane 5| will indicate the level of the pile. Thus the release of the brake occurs at a predetermined interval, nearly a half cycle, after the feeler begins its downward movement in its oscillation. On the upward stroke of the connecting rod 3|, the pin 63 will move to the right (Fig. 5) against the tension of leaf spring 6|. vane 5| because of the action of brake 52. Drum may carry a pin 54 against which spring 8! may act to aid in the alignment of the drums 49 and with respect to one another.

While the position of the vane 5| will register the height of the pile, it is desirable to provide means whereby such vane may actuate mechanism for restoring the pile to a desired level, and for this purpose servo-mechanism comprising the Sylphon bellows l'fi and attendant mechanism is provided. Bellows ii! is adjustably held in a slot ll of bracke 12 by means of a nut '53 and washer l4, and is connected with a pipe '15 transmitting air under pressure. At the other end or" the bellows a bleed valve is provided in the form of a ball PG held against its seat by means of spring "ii. The tip of the bellows to the left of the ball 15 comprises bleed passages 18, a tip. '59 containing a pin or plunger 80 which extends into contact with the ball 76. It will be noted that the air pressure tends to expand the bellows, especially since it tends to seat the ball 15, whereas the spring action of the bellows '15 is such as to contract the bellows in absence of superatmospheric air pressure. Hence if the vane 5| moves to the left in Fig. 4, the spring Tl will tend to close the valve and stop the bleeding, whereby the air pressure will expand the bellows so as to cause the tip of the bellows and the plunger 88 to follow said vane 5| to the left. Having done so, further movement of the bellows will cause the pin 88 to partially unseat the ball 16 and hence again to bleed the bellows of its air. However, the equilibrium which is set up by the position leftward of that shown in Fig. 4 results in an increased However, this will not disturb the m ay be used, the air supply in pipe 15 may be from a source established at 17 pounds per square inch gauge. The air then flows through valve 8|,

flow restrictor 82 and flow indicator 83. Thus the variation in pressure caused by the operation of the vane 5| may cause the air pressure within bellows ID to vary from 3 to say 15 pounds, corresponding, say, to the positions C and A respectively of vane 5|, Fig. 4, as would be indicated on gauge 84. This, then, will cause the complement of this pressure to occur in pipe 85 and such variation in pressure may then be caused to operate whatever control mechanism is desired to vary the feed of material into the digester l2.

Figure 8 shows an alternate, electrically actuated servo-mechanism. In this fonn of device, vane 5| constitutes an electrical contact which wipes across a resistance 90. Referring to Fig. 9, it will be seen that the resistance 90, conductor 9|, resistance 92, conductor 93, constitute the external circuit of the familiar Wheatstone bridge whereas wiper 5|, conductor 94, unbalance detector and amplifier 95, wiper 96 for resistance 92, conductor 9?, transformer secondary 98 and conductor 89 constitute with the foregoing the inner circuit. Thus when wiper 5| moves, it throws the circuit comprising detector into unbalance, thereby causing same to actuate motor Hill to move wiper 95 through connector |0| until balance is restored. At the same time, indicator I02 is also actuated. Connector |0| may also actuate recorder I03 as shown. Both the servomechanism of Fig. 9 and that comprising bellows 70 are well known per se and therefore need no further detailed description and specification.

I claim:

1. In a level indicator for a pile of solid materials, a feeler, means for periodically moving same onto said pile, a drum, an indicator proper connected thereto, a brake for said drum, a pivoted positioner element, a linkage therefrom to said feeler to move said element in accordance with the movement of the feeler onto said pile, a resilient connection between said drum and said element, said brake normally keeping said drum from following the movement of said positioner element while permitting the energy acquired by the movement of said element to be stored in said resilient connection, means for momentarily releasing said brake at a predetermined point in the periodic operation of the first named means, thereby permitting said drum to move in response to the energy stored in said resilient connection and to thereafter be held by said brake in such position.

2. In a level indicator for a pile of solid materials, a feeler, means for periodically lifting and allowing same to fall freely upon the material of said pile, a drum, an indicator proper connected thereto, a brake for said drum, a pivoted positioner element, a linkage therefrom to said feeler to move said element in accordance with the downward movement of said feeler, a resilient connection between said drum and said positioner element, said brake normally keeping said drum from following the movement of said element while permitting the energy acquired by the movement of said element to be stored in said resilient connection, means for momentarily releasing said brake at a predetermined point in the periodic operation of the first named means, thereby permitting said drum to move in response to the energy stored in said resilient connection. 7 3. In a system for indicating and/or regulating the height of a pile of divided solid material, a mechanism comprising a feeler capable of resting on the surface of said material without substantial penetration thereinto, means for periodically raising said feeler and lowering it down on to the surface of the material, an impulse storing device, means to impart thereto impulses proportionate to the upward and downward strokes of the feeler, an indicator element responsive, to said impulses, and means for releasing to said indicator element at a predetermined point in the periodic operation of the first mentioned means said impulses produced by said downward feeler stroke to the exclusion of said impulses produced by said upward feeler stroke.

4. In a system for indicating and/or regulating the height of a pile of divided solid material, a mechanism comprising a feeler capable of resting on the surface of said material without substantial penetration thereinto, means for periodically raising said feeler and lowering it down on to'the surface of the material, an'impulse storing device, a linkage connecting the same with said feeler to impart to said storing device an impulse proportionate to the downward stroke of the feeler, an indicator element responsive to said impulse, and means for releasin said impulse to said indicator element at a predetermined point in the periodic operation of the first named means.

5. In a level indicator for a pile of solids inside a pressure vessel, a feeler, a shaft for oscillating same so as to bring said feeler onto and away from said pile, a sleeve for said shaft adapted to carry same into a pressure vessel, an impulse storing device, means to impart thereto an impulse proportionate to the downward stroke of the feeler, an indicator element responsive to said impulse, and means for releasing said impulse to said indicator element at a predetermined interval following a continually recurrent point in the oscillation of said feeler.

6. In a system for indicating and/or regulating the height of a pile of divided solid material, a mechanismcomprising a feeler capable of resting on the surface of the material without substantial penetration thereinto, means for periodically raising said feeler and lowering it down' onto the surface of the material, a positioner element, a linkage connecting said positioner element with said feeler whereby to impart movement to said positioner which is proportionate to the total movement of the feeler, an indicator element, a resilient linkage connecting said positioner element with said indicator element such that the movement of said positioner element is transmitted to said indicator element when the latter is free to move, together with means for restraining the movement of the indicator elemen save during a predetermined interval within the periodic operation of the first named means whereupon the position of said positioner is transmitted to said indicator element so as to enable the latter to indicate the level of the pile.

7. In a system for indicating and/ or regulating the height of a pile of divided solid material, a mechanism comprising a feeler capable of resting on the surface of the material without substantial penetration thereinto, means for periodically raising said feeler and lowering it down onto the surface of the material, a positioner element, a linkage connecting said positioner element with said feeler whereby to impart movement to said positioner which is proportionate to the total movement of the feeler, an indicator element, a resilient linkage connecting said positioner element with said indicator element such that the movement of said positioner element is transmitted to said indicator element when the latter is free to move, together with means for restraining the movement of the indicator element comprising a brake and means for releasing same during a predetermined interval within the periodic operation of the first named means.

8. In a system for indicating and/or regulating the height of a pile of divided solid material, a mechanism comprising a feeler capable of resting on the surface of the material without substantial penetration thereinto, means for periodically raisin said feeler and lowering it down onto the surface of the material, a positioner element, a linkage connecting said positioner element with said feeler whereby to impart movement to said positioner which is proportionate to the total movement of the feeler, an indicator element, a resilient linkage connecting said positioner element with said indicator element such that the movement of said positioner element is transmitted to said indicator element when the latter is free to move, together with means for restraining the movement of the indicator element comprising a brake, and linkage between said feeler raising means and said brake for releasing the latter during a predetermined interval within the periodic'operation of the first named means.

9. In a device for measuring and controlling the level of a granular-like solid material, a feeler capable of resting on the surface of the material without sinking thereinto, a continuously rotating crank with linkage system for raising said feeler above the level of the material and lowering it down onto the surface of the material, a first indicator arm connected with the feeler indicatin the position of the feeler at all times, a second indicator arm flexibly connected with said first indicator arm and adapted to move in conjunction with said first indicator arm, a friction brake arranged to restrain said second indicator arm, together with means for releasing said brake during a predetermined interval periodically recurrent in the movement of said crank.

References Cited in the file of this patent UNITED STATES PATENTS Genovese Sept. 18, 1951 

